Validation of Molecular Markers for Breeding High Antioxidant Traits in Thai Rice

This research attempted to validate novel molecular markers linked to high antioxidant traits using an F2 population and a local Thai rice population. We performed total flavonoid content, total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) assays to assess the antioxidant capacities of rice populations. In the F2 (“Pathum Thani 1” × “Hawm Mali Daeng”) population, these traits exhibited a quantitative distribution with high heritability (82.7%–98.3%) and high genetic advance (66%–94%). In validation using 10 molecular markers, OsRc and In1-Rc displayed polymorphism in parent cultivars and in bulked segregant analysis. However, only OsRc had strong associations with TPC (R2 = 52.2%, p < 0.001) and FRAP (R2 = 43.0%, p < 0.001), whereas In1-Rc featured no significant associations (R2 ≤ 0.1%). When verified in Thai rice cultivars, OsRc could discriminate red pericarp rice cultivars with high antioxidant properties from white pericarp cultivars with low antioxidant activity, confirming its efficiency in selecting antioxidant traits in rice. These findings indicate that OsRc is a functional marker for selecting rice lines with high antioxidant activity, thereby facilitating early-stage genotyping in rice breeding programs